Heroes are the biggest power spike per Town Hall
No single upgrade changes an account like a hero level. Heroes are permanent units that carry every attack, and their abilities — the Barbarian King's rage, the Archer Queen's cloak, the Grand Warden's aura and life pulse, the Royal Champion's shield — scale directly with their level. That is why a base with maxed defenses but under-leveled heroes still underperforms in war. The table above lists all seven heroes we level, which village each belongs to, and the resource each one costs.